1. Field of the Invention
The present invention generally relates to a method of fabricating a semiconductor device. More particularly, the present invention relates to a method of fabricating a read only memory (ROM) and a memory cell array.
2. Description of Related Art
As microprocessor programming and calculating capabilities using software are being continuously enhanced are highly demanded, processes for manufacturing memory device is of great importance in semiconductor processing technology.
Generally, memory devices can be divided into volatile memory devices and non-volatile memory devices according to storage type thereof. Data stored in the volatile memory device disappears when power supply to the non-volatile memory device is removed. Hence, the volatile memory device is usually utilized to store turn-on data in a computer.
Currently, many methods of fabricating memory device are being developed for reducing memory device dimension. However, memory device size reduction causes short channel effect due to corresponding channel length reduction. One approach is to inhibit short channel effect by increasing doping concentration of channel. But, too great a doping concentration of the channel may lead to current leakage.
In order to increase the integration of memory device, the space between adjacent memory cells must be reduced. However, the space between adjacent memory cells is limited due to the limitation of lithography process.